Arsene Wenger has admitted that Arsenal were at fault after former player Alexis Sanchez missed a drugs test ahead of his switch to Manchester United.

The Chilean forward was due to be tested on Monday when finalising a switch between the two clubs, which the Gunners inadvertently kept quiet from the Football Association and UK Anti-Doping chiefs.

Sanchez is said to have fallen foul of the FA's "whereabouts" rule by not being present, but Wenger insists that his side "have nothing to hide" as it was an honest mistake on their behalf.

"The most important is that the intention is right," he told reporters at Friday's press conference. "The intention of Alexis was certainly not to hide - nor was our intention to hide anything. We have nothing to hide.

"I'm quite relaxed because we have nothing to hide here, we always try our best to co-operate with doping control. I pushed always for football to do more against doping so I don't see why we shouldn't co-operate. We try our best but this was a special day.

"You have to do paperwork, you have to travel and is he still our player on Monday or not? You don't know with negotiations going on. I think it's a special event for him to miss a drug test because he was certainly busy somewhere else with his agent.

"Overall he has been tested so many times here that it is no worry for me that he has any doping problem. It's just a bad day for him to be tested. Honestly on the administration side it would certainly be our responsibility because on the day he had not moved so maybe it will be down to us. I don't really know what happened."

Sanchez's move to Man United was announced at 6pm on Monday evening, with Henrikh Mkhitaryan heading the opposite way in a straight swap deal.